Control circuit for a sensor, an electrical control unit for a wheel speed sensor, a method of operating a wheel speed sensor, a method of controlling a sensor and a computer program

ABSTRACT

A control circuit for a wheel speed sensor is provide. The control circuit includes an input interface configured to receive high-resolution wheel speed data and low-resolution wheel speed data; and circuitry configured to determine information on a functional state of the wheel speed sensor using the high-resolution data and the low-resolution data. The circuitry is configured to detect a failure state of the wheel speed sensor if a number of signal events which are signaled by the high-resolution wheel speed data between a first signal event and a second signal event deviates from an expected number. The first signal event and the second signal event are signaled by the low-resolution wheel speed data.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.17/314,216, filed May 7, 2021 (now U.S. Pat. No. 11,614,458), which isincorporated herein by reference in its entirety.

FIELD

Examples relate to a control circuits for sensors, electrical controlunits for wheel speed sensors, methods of operating wheel speed sensors,methods of controlling sensors and computer programs.

BACKGROUND

Wheel speed sensors can be used to determine a rotational speed andoptionally also a direction of rotation of a wheel. In someimplementations, the movement of the wheel causes a change in a magneticfield of the sensor by means of an encoder. Wheel speed sensors may, forexample, comprise Hall elements to detect the change of the magneticfield. The Hall elements generate an alternating voltage signal whilethe wheel is in rotation. The alternating voltage signal value can beencoded into digital output protocols to signal the rotational speedand/or the direction in a speed or direction channel.

Some speed sensors implement a crosscheck mechanism which can activate asafety mechanism by comparing the signals of the speed and directionchannels. The crosscheck mechanism can determine information on afunctional state of the sensor.

There is still a demand to improve an operation or control of sensors tomake conclusions on their functional states.

SUMMARY

According to an embodiment, a control circuit for a sensor thatdetermines a sensed property comprises an input interface configured toreceive high-resolution data and low-resolution data for the sensedproperty. The control circuit further comprises circuitry configured todetermine information on a functional state of the sensor using thehigh-resolution data and the low-resolution data. Comparing thehigh-resolution data and low-resolution data for the sensed property mayallow conclusions to be made on the functional state of the sensor, forexample by performing consistency checks.

An embodiment of an electrical control unit (ECU) for a wheel speedsensor comprises an input interface configured to receivehigh-resolution data and low-resolution data for an angle measured bythe wheel speed sensor. The electrical control unit further comprisescircuitry configured to determine information on a functional state ofthe wheel speed sensor using the high-resolution data and thelow-resolution data. Since both data describe an identical rotation,comparison between high-resolution data and low-resolution data orconsistency checks based on said data may allow a conclusion to be madewhether the functional state of the wheel speed sensor is as expected.

BRIEF DESCRIPTION OF THE DRAWINGS

Some examples of apparatuses and/or methods will be described in thefollowing by way of example only, and with reference to the accompanyingfigures, in which

FIG. 1 illustrates an embodiment of a control circuit for a sensor;

FIG. 2 illustrates an embodiment of an electrical control unit for awheel speed sensor;

FIG. 3 illustrates an example for high-resolution data andlow-resolution data of a wheel speed sensor;

FIG. 4 illustrates a first example for inconsistent high andlow-resolution data of the wheel speed sensor;

FIG. 5 illustrates a second example for inconsistent high andlow-resolution data of the wheel speed sensor;

FIG. 6 illustrates a third example for inconsistent high andlow-resolution data;

FIG. 7 illustrates a fourth example for inconsistent high andlow-resolution data;

FIG. 8 illustrates a flow chart of an embodiment of a method ofoperating a wheel speed sensor; and

FIG. 9 illustrates another flow chart of an embodiment of a method forcontrolling a sensor.

DETAILED DESCRIPTION

Various examples will now be described more fully with reference to theaccompanying drawings in which some examples are illustrated. In thefigures, the thicknesses of lines, layers and/or regions may beexaggerated for clarity.

Accordingly, while further examples are capable of various modificationsand alternative forms, some particular examples thereof are shown in thefigures and will subsequently be described in detail. However, thisdetailed description does not limit further examples to the particularforms described. Further examples may cover all modifications,equivalents, and alternatives falling within the scope of thedisclosure. Same or like numbers refer to like or similar elementsthroughout the description of the figures, which may be implementedidentically or in modified form when compared to one another whileproviding for the same or a similar functionality.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, the elements may bedirectly connected or coupled via one or more intervening elements. Iftwo elements A and B are combined using an “or”, this is to beunderstood to disclose all possible combinations, i.e. only A, only B aswell as A and B, if not explicitly or implicitly defined otherwise. Analternative wording for the same combinations is “at least one of A andB” or “A and/or B”. The same applies, mutatis mutandis, for combinationsof more than two Elements.

The terminology used herein for the purpose of describing particularexamples is not intended to be limiting for further examples. Whenever asingular form such as “a,” “an” and “the” is used and using only asingle element is neither explicitly or implicitly defined as beingmandatory, further examples may also use plural elements to implementthe same functionality. Likewise, when a functionality is subsequentlydescribed as being implemented using multiple elements, further examplesmay implement the same functionality using a single element orprocessing entity. It will be further understood that the terms“comprises,” “comprising,” “includes” and/or “including,” when used,specify the presence of the stated features, integers, steps,operations, processes, acts, elements and/or components, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, processes, acts, elements, componentsand/or any group thereof.

Unless otherwise defined, all terms (including technical and scientificterms) are used herein in their ordinary meaning of the art to which theexamples belong.

FIG. 1 illustrates an embodiment of a control circuit 100 for a sensor102 that determines a sensed property. The sensed property may bearbitrary, for example, a magnetic field, intensity of light, an angle,a distance or a shape of an object. The control circuit 100 for thesensor 102 comprises an input interface 104 configured to receivehigh-resolution data and low-resolution data for the sensed property.For example, the data may signal events sensed by the sensor by adigital or analog protocol. An event may, for example, be signaled everytime the sensed property exhibits a specific state or quantity. In theevent of a wheel speed sensor sensing a magnetic field strength, anevent may, for example, be signaled every time the alternating voltageoutput of magnetic sensor elements crosses zero. For sensors discussedherein, high-resolution data may correspond to sensing of a first typeof event and the low-resolution data may correspond to sensing of asecond type of event. Hence, received data may comprise different eventrecords and a different number of event records of high-resolution dataand low high-resolution data at a given time interval.

The control circuit 100 further comprises circuitry 106 configured todetermine information on a functional state of the sensor 102 using thehigh-resolution data and the low-resolution data. The determinedfunctional state of the sensor 102 may indicate proper functioning ifthe received data is consistent. Likewise, the functional state of thesensor 102 may indicate malfunction if the received data isinconsistent. Since high-resolution data and low-resolution data bothdescribe the identical sensed property, the circuitry can determine thefunctional state of the sensor by analyzing the high-resolution datawith the low-resolution data with respect to their consistency.

In an embodiment of the control circuit 100 the input interface 104 isconfigured to receive high-resolution data indicative of a firstincrement of the sensed property. Further, the input interface 104 isconfigured to receive low-resolution data indicative of a secondincrement of the sensed property, wherein the second increment is biggerthan the first increment. Such high-resolution data and low-resolutiondata is, for example, received by a controller of a wheel speed sensordiscussed subsequently. In another example, the sensed property may be adistance continuously measured by the sensor 102. The sensor 102 mayrecord an event at each increment the distance changes. For example, thefirst increment may equal 10 cm for the high-resolution data and thesecond increment may equal 40 cm for the low-resolution data. Since thesecond increment is bigger than the first increment, eventscorresponding to the high-resolution data may be sensed more frequentlycompared to events corresponding to low-resolution data. In thepreviously given example, for every increment signaled by thelow-resolution data, 4 increments signaled by the high-resolution datais expected. If this ratio is not observed, one may make a conclusionwhether there is an error in the sensor of any kind.

In an embodiment of the control circuit 100, the input interface 104 mayfurther be configured to receive a signal of a first signal type if thesensed property changed by the first increment and a signal of a secondsignal type if the sensed property changed by the second increment. Forthe previously described example the signal of the first signal type maybe received every time the sensor senses a change of the distance by 10cm and the signal of the second signal type may be received every timethe sensor senses a change of the distance by 40 cm. The signals of thefirst and the second signal type depend on the chosen protocol, and may,for example, be distinguished by their height, intensity, frequency,duration, modulation of the signal, or by other characteristics.

According to an embodiment of the control circuit 100 receivingdifferent signal types for different events, the circuitry 106 isfurther configured to determine a failure state of the sensor 102 if anumber of signals of the first signal type received between a pair ofconsecutive signals of the second signal type deviates from an expectednumber. As elaborated on before, a particular signal sequence can beexpected in such applications and deviation from that sequence mayindicate an error.

In another embodiment, the circuitry 106 is configured to determine afailure state of the sensor if a number of signals of the first signaltype received consecutively without receiving a signal of the secondsignal type exceeds an expected number. Considering the previouslydescribed example after a signal of the second type, one may expect toreceive three signals of the first signal type before another signal ofthe second signal is received. Hence, if four signals of the firstsignal type are received consecutively without receiving a signal of thesecond signal type the failure state of the sensor can be alreadydetermined. A failure state of the sensor can be determined withoutwaiting for the reception of the second signal type, which allows todetermine a failure state of a sensor faster than waiting for twosubsequent signals of the second type.

Embodiments of the control circuit are not restricted to particularsensors. The associated sensors can be of different types detectingphysical or chemical properties such as temperature, pressure, speed,electromagnetic field, electrochemical potential, brightness, acousticor optical signal, pH-number and so on.

Depending on the type of sensor, the sensed property can be used todetermine, e.g. a distance, an angle, an arc length, an intensity, afield strength, a time difference, a force, a torque, an acceleration, adensity, a frequency, a concentration and much else.

FIG. 2 illustrates another embodiment of the invention comprising anelectrical control unit 200 for a wheel speed sensor 202 using e.g. agear or an increment wheel 201 as an encoder. The wheel speed sensor 202can be used in automotive industry such as for measuring a speed of agear shaft, a speed of wheels, a position of a gear to trigger ignition,a direction of motion of a wheel and much else. The electrical controlunit 200 for the wheel speed sensor 202 comprises an input interface 204configured to receive high-resolution data and low-resolution data foran angle measured by the wheel speed sensor 202. The wheel speed sensor202 can detect the angle of deflection caused by the rotation of thewheel 201. The evaluated signals may be generated by a change ofmagnetic field caused by the appearance and absence of teeth of the gear201 or by permanent magnets arranged on the increment wheel 201. Inducedsignals can be encoded into data which can be sent to the inputinterface 204. For example, depending on the motion of the teeth of thegear or of the magnets on the increment wheel a high-resolution andlow-resolution data can be generated and received by the input interface204. High-resolution data can determine a smaller angle of deflectionthan low-resolution data.

The electrical control unit 200 comprises circuitry 206 configured todetermine information on a functional state of the wheel speed sensor202 using the high-resolution data and the low-resolution data. The highand low-resolution data corresponds to the motion and known constitutionof the wheel. Hence, by comparing high-resolution and low-resolutiondata, a functional state of the wheel speed sensor 202 can bedetermined. If high-resolution data and low-resolution data areinconsistent or do not match, a malfunction of the wheel speed sensor202 can be assumed.

According to the embodiment illustrated in FIG. 2 the input interface204 is further configured to receive high-resolution data indicative ofa number of changes of a first increment of the angle and low-resolutiondata indicative of a number of changes of a second increment of theangle, wherein the second increment is bigger than the first increment.For example, the gear 201 comprises 60 teeth arranged by an angle of 6°corresponding to one cycle of e.g. a sinusoidal signal. The secondincrement of the angle can be 3° considering the angle between two zerocrossings of the sinusoidal signal. The second increment of the anglecan be considered in more detail by using the first increment of theangle to increase the resolution. For example, the first increment ofthe angle can be 1.5°. The second increment is bigger than the firstincrement such that a number of changes of the first increment isindicative of high-resolution data and the number of changes of thesecond increment is indicative of low-resolution data. The secondincrement may correspond e.g. to the arrangement of the teeth of thegear 201 or on the arrangement of permanent magnets 201 on the incrementwheel. The first increment may correspond to e.g. fine-tuned patternsappearing along the second increments or more generally, along the wheel201.

In the embodiment of the electrical control unit 200 the circuitry 206is further configured to determine a failure state of the wheel speedsensor 202. The failure state is determined, if a number of changes ofthe first increment for a single change of the second increment deviatesfrom an expected number. According to the previously described examplecomprising a first increment of 1.5° and a second increment of 3° for asinusoidal signal with a cycle of 6°, the expected number of changes of1.5° within a single change of 3° may be equal to one on the conditionof a uniform arrangement of increments and a uniform motion of the wheel201. If the number of changes of first increments within a single changeof second increment is not equal to one, the failure state isdetermined. It can be assumed that the sensor is not working properly asthe expectations are not met.

According to another embodiment of the electrical control unit 200, thecircuitry 206 is configured to determine a failure state of the wheelspeed sensor 202 if a number of consecutive changes of the firstincrement without a single change of the second increment exceeds anexpected number. Compared to the previously described embodiment of theelectrical control unit 200 the failure state of the wheel speed sensor202 can be determined more quickly. If the number of consecutive changesof first increment of 1.5° exceeds the expected number of one within atotal range of 3°, the failure state can be determined. Hence, thefailure state can be determined if two consecutive changes of the firstincrement are received without a single change of the second increment.After exceeding the expected number, the reception of further data bythe input interface can be neglected as further data will not be able toachieve the expected number subsequently.

In an embodiment of the invention an electrical control unit 200 isconfigured to change an operation mode from normal operation to failsafeoperation if the failure state is determined. The electrical controlunit 200 can change operation modes which may have the consequence tochange the condition or function of corresponding hardware or software.If the failure state is determined the electrical control unit 200 canchange to failsafe operation e.g. to interrupt processes or triggeradditional safety actions or arrangements such as anti-lock brakingsystem (ABS), electric power steering (EPS), traction control system(TCS), autonomous parking, hill holder, electric engine control andothers.

According to the embodiment, the electrical control unit 200 is furtherconfigured to transmit a reset signal if the failure state is determinedwhere the reset signal causes the wheel speed sensor to reset. Resettingthe wheel speed sensor may be for example initializing the position ofthe wheel compared to the wheel speed sensor, calibrating the wheelspeed sensor, rebooting the wheel speed sensor, turning off the wheelspeed and much more.

An embodiment of a wheel speed sensor 202, comprises an input interface204 configured to receive high-resolution data and low-resolution datafor an angle measured by the wheel speed sensor 202. The wheel speedsensor 202 further comprises circuitry 206 configured to determineinformation on a functional state of the wheel speed sensor 202 usingthe high-resolution data and the low-resolution data.

According to the embodiment, the wheel speed sensor 202 is furtherconfigured to automatically reset if the failure state is determined.For example, if a persistent failure state is determined, the wheelspeed sensor 202 can change automatically in function, state, processingor in other ways.

For better understanding an application of the control circuit or theelectrical control unit is discussed in more detail in FIG. 3 using aparticular example of a data transmission protocol. An input interfacereceives low-resolution data by means of signals of a first signal typegiven by peak 307 and high-resolution data by means of signals of asecond signal type given by peak 308. The protocol may, for example,distinguish between the different signal types by means of theirdifferent height or amplitude. Low-resolution data indicateszero-crossings of a speed signal 309. The speed signal may be generatedby a sensor element measuring the field strength variations caused bywheel 201. High-resolution data indicates equally spaced phases of thesinusoidal signal 309 and, hence, the rotation of the wheel 201 with ahigher resolution. In the example of FIG. 3 , the expected number ofhigh-resolution events 308 between two subsequent low-resolution events307 equals N=2 if the wheel moves in the same direction.

A deviation of the number of high-resolution events as compared to thelow-resolution events may be due to four different scenarios. In thefirst scenario the sensor indicates additional zero-crossings. In thesecond scenario, the sensor loses a zero-crossing. In the thirdscenario, the sensor provides an additional high-resolution event. Andin the fourth scenario, the sensor loses a high-resolution event.

If between two zero-crossing events/protocols there are less than N=2high-resolution events/protocols it means that either the first scenarioor the fourth scenario have been violated. This means that azero-crossing protocol has been added or a high-resolution protocol hasbeen lost.

If more than N=2 high-resolution protocols are observed consecutively inthe same direction, it means that either the second scenario or thethird scenario has been violated. This means, that a zero-crossingprotocol has been lost or a high-resolution protocol has been added.

Each scenario corresponds to a deviation from an expected ratio ofevents. As a consequence, a failure state of the sensor is determined bythe circuitry. For example, a safety mechanism can be activated toinform the electronic control unit and to bring a system into a safestate. If the failure state persists the electrical control unit can actas a watchdog transmitting a reset signal causing the wheel speed sensorto reset.

FIGS. 4 to 7 illustrate examples for high and low-resolution datadeviating from an expectation. All figures use the signals introduced inFIG. 3 . In the event a failure state is determined, the figures furtherillustrate a failure signal 400 that is generated for the duration thefailure persists.

FIG. 4 illustrates the generation of the failure signal 400 since toomany high-resolution events are received between two consecutivelow-resolution events.

FIG. 5 illustrates the generation of the failure signal 400 since toofew high-resolution events or protocols are received between twosubsequent low-resolution events.

FIG. 6 illustrates the generation of the failure signal 400 since toomany low-resolution events are received.

FIG. 7 illustrates the generation of the failure signal 400 since toofew low-resolution events are received.

FIG. 8 illustrates a flow chart of an embodiment of a method ofoperating a wheel speed sensor 800. The method 800 comprises receivinghigh-resolution data and low-resolution data for an angle measured bythe wheel speed sensor 801. The method further comprises determininginformation on a functional state of the wheel speed sensor using thehigh-resolution data and the low-resolution data 802.

FIG. 9 illustrates another flow chart of an embodiment of a method forcontrolling a sensor 900. The method comprises receiving high-resolutiondata and low-resolution data for the sensed property 901. The methodfurther comprises determining information on a functional state of thesensor using the high-resolution data and the low-resolution data 902.

Another embodiment of the invention comprises a computer program havinga program code configured to cause performing a method according to thepreviously described control circuit or electrical control unit if thecomputer program is executed by a programmable hardware component.

For example, the previously described electrical control unit may beimplemented by a program comprising an algorithm that checks if thesequence of zero-crossing protocols and high-resolution protocols isconsistent with expectations. The algorithm can enable a safetymechanism or reset the sensor in case of a persistent failure state ofthe sensor remains, e.g. when the number of high-resolution protocolsbetween two zero-crossing protocols is either too high or too low. Thealgorithm can prevent the violation of the described four scenarios e.g.due to systematic or random hardware error.

Embodiments of the invention can interact with a customer system. Thesensor can be connected to the ECU, which can calculate the speed,rotational direction and movement of the target wheel. The sensor canprovide an output signal encoded in AK or PWM protocol. Customers canuse the information from the sensor for various applications such asautomotive features as described before. Embodiments of the inventioncan be used also in other applications such as for transmission, engineor angle sensors. Embodiments of control circuits or ECUs may improvethe safety concept of sensors and hence also the safety performance of afull system. As an example, a high-resolution wheel speed sensor withextended cross check mechanism can be developed to improve an alreadyexisting wheel speed sensor. An accordingly upgraded Sensor may enableautonomous driving and parking applications at a high safety level.

The aspects and features mentioned and described together with one ormore of the previously detailed examples and figures, may as well becombined with one or more of the other examples in order to replace alike feature of the other example or in order to additionally introducethe feature to the other example.

Examples may further be or relate to a computer program having a programcode for performing one or more of the above methods, when the computerprogram is executed on a computer or processor. Steps, operations orprocesses of various above-described methods may be performed byprogrammed computers or processors. Examples may also cover programstorage devices such as digital data storage media, which are machine,processor or computer readable and encode machine-executable,processor-executable or computer-executable programs of instructions.The instructions perform or cause performing some or all of the acts ofthe above-described methods. The program storage devices may comprise orbe, for instance, digital memories, magnetic storage media such asmagnetic disks and magnetic tapes, hard drives, or optically readabledigital data storage media. Further examples may also cover computers,processors or control units programmed to perform the acts of theabove-described methods or (field) programmable logic arrays ((F)PLAs)or (field) programmable gate arrays ((F)PGAs), programmed to perform theacts of the above-described methods.

The description and drawings merely illustrate the principles of thedisclosure. Furthermore, all examples recited herein are principallyintended expressly to be only for illustrative purposes to aid thereader in understanding the principles of the disclosure and theconcepts contributed by the inventor(s) to furthering the art. Allstatements herein reciting principles, aspects, and examples of thedisclosure, as well as specific examples thereof, are intended toencompass equivalents thereof.

A functional block denoted as “means for . . . ” performing a certainfunction may refer to a circuit that is configured to perform a certainfunction. Hence, a “means for something” may be implemented as a “meansconfigured to or suited for something”, such as a device or a circuitconfigured to or suited for the respective task.

Functions of various elements shown in the figures, including anyfunctional blocks labeled as “means”, “means for providing a signal”,“means for generating a signal.”, etc., may be implemented in the formof dedicated hardware, such as “a signal provider”, “a signal processingunit”, “a processor”, “a controller”, etc. as well as hardware capableof executing software in association with appropriate software. Whenprovided by a processor, the functions may be provided by a singlededicated processor, by a single shared processor, or by a plurality ofindividual processors, some of which or all of which may be shared.However, the term “processor” or “controller” is by far not limited tohardware exclusively capable of executing software, but may includedigital signal processor (DSP) hardware, network processor, applicationspecific integrated circuit (ASIC), field programmable gate array(FPGA), read only memory (ROM) for storing software, random accessmemory (RAM), and non-volatile storage. Other hardware, conventionaland/or custom, may also be included.

A block diagram may, for instance, illustrate a high-level circuitdiagram implementing the principles of the disclosure. Similarly, a flowchart, a flow diagram, a state transition diagram, a pseudocode, and thelike may represent various processes, operations or steps, which may,for instance, be substantially represented in computer readable mediumand so executed by a computer or processor, whether or not such computeror processor is explicitly shown. Methods disclosed in the specificationor in the claims may be implemented by a device having means forperforming each of the respective acts of these methods.

It is to be understood that the disclosure of multiple acts, processes,operations, steps or functions disclosed in the specification or claimsmay not be construed as to be within the specific order, unlessexplicitly or implicitly stated otherwise, for instance for technicalreasons. Therefore, the disclosure of multiple acts or functions willnot limit these to a particular order unless such acts or functions arenot interchangeable for technical reasons. Furthermore, in some examplesa single act, function, process, operation or step may include or may bebroken into multiple sub-acts, -functions, -processes, -operations or-steps, respectively. Such sub-acts may be included and part of thedisclosure of this single act unless explicitly excluded.

Furthermore, the following claims are hereby incorporated into thedetailed description, where each claim may stand on its own as aseparate example. While each claim may stand on its own as a separateexample, it is to be noted that, although a dependent claim may refer inthe claims to a specific combination with one or more other claims,other examples may also include a combination of the dependent claimwith the subject matter of each other dependent or independent claim.Such combinations are explicitly proposed herein unless it is statedthat a specific combination is not intended. Furthermore, it is intendedto include also features of a claim to any other independent claim evenif this claim is not directly made dependent to the independent claim.

What is claimed is:
 1. A control circuit for a wheel speed sensor, thecontrol circuit comprising: an input interface configured to receivehigh-resolution wheel speed data and low-resolution wheel speed data;and circuitry configured to determine information on a functional stateof the wheel speed sensor using the high-resolution wheel speed data andthe low-resolution wheel speed data, wherein the circuitry is configuredto detect a failure state of the wheel speed sensor if a number ofsignal events which are signaled by the high-resolution wheel speed databetween a first signal event and a second signal event deviates from anexpected number, and wherein the first signal event and the secondsignal event are signaled by the low-resolution wheel speed data.
 2. Thecontrol circuit according to claim 1, wherein the circuitry isconfigured to determine a direction of rotation of a wheel that isassociated with the high-resolution wheel speed data and thelow-resolution wheel speed data, and wherein the circuitry is configuredto detect the failure state of the wheel speed sensor if the number ofsignal events which are signaled by the high-resolution wheel speed databetween the first signal event and the second signal event deviates fromthe expected number and if the signal events corresponding to the numberof signal events are signaled while the wheel rotates in a samedirection of rotation.
 3. The control circuit according to claim 1,wherein the circuitry is configured to detect the failure state if thecircuitry detects one of the following: the number of signal eventssignaled by the high-resolution wheel speed data between the firstsignal event and the second signal event are signaled during a samerotation direction and the number of signal events is less than theexpected number, or the number of signal events signaled by thehigh-resolution wheel speed data are signaled during a same rotationdirection, the number of signal events are signaled without a signalevent signaled by the low-resolution wheel speed data occurring betweenthe first signal event and the second signal event, and the number ofsignal events exceeds the expected number.
 4. A control circuit for awheel speed sensor, the control circuit comprising: an input interfaceconfigured to receive high-resolution wheel speed data andlow-resolution wheel speed data; and circuitry configured to determineinformation on a functional state of the wheel speed sensor using thehigh-resolution wheel speed data and the low-resolution wheel speeddata, wherein the circuitry is configured to determine a number ofconsecutive signal events which are signaled by the high-resolutionwheel speed data between a first signal event and a second signal event,wherein the first signal event and the second signal event are signaledby the low-resolution wheel speed data, and wherein the circuitry isconfigured to detect a failure state of the wheel speed sensor if thenumber of consecutive signal events deviates from an expected number. 5.The control circuit according to claim 4, wherein the number ofconsecutive signal events correspond to a same rotation direction of awheel that is associated with the high-resolution wheel speed data andthe low-resolution wheel speed data.
 6. The control circuit according toclaim 4, the circuitry is configured to monitor a rotation direction ofa wheel that is associated with the high-resolution wheel speed data andthe low-resolution wheel speed data and count the consecutive signalevents that occur between the first signal event and the second signalevent while the wheel rotates in a same rotation direction to determinethe number of consecutive signal events.
 7. The control circuitaccording to claim 6, wherein the consecutive signal eventscorresponding to the number of consecutive signal events occur without asignal event signaled by the low-resolution wheel speed data beingsignaled between the first signal event and the second signal event. 8.The control circuit according to claim 4, wherein the circuitry isconfigured to detect the failure state if the circuitry detects one ofthe following: the number of consecutive signal events signaled by thehigh-resolution wheel speed data between the first signal event and thesecond signal event are signaled during a same rotation direction of awheel and the number of consecutive signal events is less than theexpected number, or the number of consecutive signal events signaled bythe high-resolution wheel speed data are signaled during a same rotationdirection, the number of consecutive signal events are signaled withouta signal event signaled by the low-resolution wheel speed data occurringbetween the first signal event and the second signal event, and thenumber of consecutive signal events exceeds the expected number.
 9. Amethod of operating a control circuit of a wheel speed sensor,comprising: receiving high-resolution wheel speed data andlow-resolution wheel speed data; determining a functional state of thewheel speed sensor using the high-resolution wheel speed data and thelow-resolution wheel speed data, including: detecting a failure state ofthe wheel speed sensor if a number of signal events which are signaledby the high-resolution wheel speed data between a first signal event anda second signal event deviates from an expected number, wherein thefirst signal event and the second signal event are signaled by thelow-resolution wheel speed data.
 10. The method according to claim 9,further comprising: determining a direction of rotation of a wheel thatis associated with the high-resolution wheel speed data and thelow-resolution wheel speed data, and detecting the failure state of thewheel speed sensor if the number of signal events which are signaled bythe high-resolution wheel speed data between the first signal event andthe second signal event deviates from the expected number and if thesignal events corresponding to the number of signal events are signaledwhile the wheel rotates in a same direction of rotation.
 11. The methodaccording to claim 9, wherein detecting the failure state includes:detecting the failure state if the number of signal events signaled bythe high-resolution wheel speed data between the first signal event andthe second signal event are signaled during a same rotation directionand the number of signal events is less than the expected number, ordetecting the failure state if the number of signal events signaled bythe high-resolution wheel speed data are signaled during a same rotationdirection, the number of signal events are signaled without a signalevent signaled by the low-resolution wheel speed data occurring betweenthe first signal event and the second signal event, and the number ofsignal events exceeds the expected number.
 12. The method according toclaim 9, further comprising: detecting a non-failure state of the wheelspeed sensor if the number of signal events which are signaled by thehigh-resolution wheel speed data between the first signal event and thesecond signal event is equal to the expected number.